The number of people dead or missing after one of the world's strongest typhoons struck the Philippines climbed towards 7,000 on Saturday, as the United Nations warned much more needed to be done to help desperate survivors.

The government's confirmed death toll rose to 5,235, with another 1,613 people still missing more than two weeks after Super Typhoon Haiyan destroyed entire towns across a long stretch of islands in the central Philippines.

Haiyan now rivals a 1976 tsunami on the southern island of Mindanao as the deadliest recorded natural disaster to strike the Philippines, which endures a never-ending battle against typhoons, earthquakes, floods and volcanic eruptions.

The typhoon has triggered a giant, international aid effort, with dozens of countries and relief organisations rushing to deliver food, water and health services to more than four million people who lost their homes.

However UN humanitarian chief Valerie Amos, after visiting the disaster zones, warned the world was still not responding fast enough.

"Much more needs to be done. Food, clean water and shelter remain the top priorities," Amos said as a UN appeal for funds was raised from $301 million to $348 million.

Amos said huge numbers of people were still exposed to bad weather in the nine provinces ravaged by the storm, as she warned particularly of the dangers for babies, children and mothers.

"I am very concerned that some 1.5 million children are at risk of acute malnutrition and close to 800,000 pregnant and nursing mothers need nutritional help," Amos told a news conference at UN headquarters.

Survivors plead for more help

In the coastal city of Tacloban, one of the worst-hit areas where five-metre (16-feet) waves surged deep inland and destroyed most buildings, survivors continued to complain about a lack of help.

"There is no steady supply of relief goods. It comes in trickles," said Maribel Senase, 41, as she held a baby and her husband sawed wood near their shattered home.

Senase, who has four children, said her family had received rice, dried fish and sardines, but they remained hungry.

The World Bank on Friday added $480 million in emergency aid to the Philippines, taking its support to nearly $1 billion, in an effort to spur efforts to rebuild homes and infrastructure.

The Asian Development Bank also last week offered $500 million concessionary loans.

The US military has performed the highest-profile role in the relief effort, sending an aircraft carrier that arrived six days after the disaster which finally allowed relief supplies to start reaching isolated communities.

Japan also sent more than 1,000 troops aboard three vessels that arrived on Thursday night, in what is the biggest overseas deployment of the country's military since its defeat in World War II nearly 70 years ago.

China, which is embroiled in a long-running territorial dispute with the Philippines, dispatched a 300-bed hospital ship, while Australia, Britain and Indonesia are among many other nations to have also sent military support.

Death toll keeps climbing

The number of people confirmed killed jumped by nearly 1,200 on Friday to 5,209, as confirmed body counts were made in some flattened communities, the spokesman for the government's disaster management council, Reynaldo Balido, told AFP.

"If you notice, there was not much movement in the death toll for the past few days. This was because the reporting rules required a casualty report signed by the city mayor and his health officer," he told AFP on Friday night.

"Now, the reports are coming in from the entire typhoon area."

The death toll rose marginally again on Saturday morning, and was expected to continue rising over the coming days and weeks.

In Tacloban, the capital of Leyte province in the eastern Philippines, 1,727 people have been confirmed dead. Another 451 remain missing.

The typhoon on November 8 brought some of the strongest winds ever recorded and generated tsunami-like storm surges that flattened dozens of towns.

The magnitude of the disaster has continued to stun and overwhelm President Benigno Aquino's administration. A few days after Haiyan struck, Aquino said he expected the death toll would be between 2,000 and 2,500.

The Philippines is so prone to natural disasters because it is located along a typhoon belt and the so-called Ring of Fire, a vast Pacific Ocean region where many of Earth's earthquakes and volcanic eruptions occur.

But the only other natural disaster to compare with Haiyan for ferocity was the tsunami triggered by a magnitude 7.9 earthquake in 1976 that killed between 5,000 and 8,000 people on Mindanao.